Communication system noise cancellation power signal calculation techniques

Abstract

In order to enhance the quality of a communication signal derived from speech and noise, a filter divides the communication signal into a plurality of frequency band signals. A calculator generates a plurality of power band signals each having a power band value and corresponding to one of the frequency band signals. The power band values are based on estimating, over a time period, the power of one of the frequency band signals. The time period is different for different ones of the frequency band signals. The power band values are used to calculate weighting factors which are used to alter the frequency band signals that are combined to generate an improved communication signal.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application is a continuation of U.S. application Ser. No. 10 / 376,849, filed Feb. 28, 2003, which is a continuation of U.S. application Ser. No. 09 / 536,941, filed Mar. 28, 2000, now U.S. Pat. No. 6,529,868 B1.STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT [0002] Not applicable. BACKGROUND OF THE INVENTION [0003] This invention relates to communication system noise cancellation techniques, and more particularly relates to calculation of power signals used in such techniques. [0004] The need for speech quality enhancement in single-channel speech communication systems has increased in importance especially due to the tremendous growth in cellular telephony. Cellular telephones are operated often in the presence of high levels of environmental background noise, such as in moving vehicles. Such high levels of noise cause significant degradation of the speech quality at the far end receiver. In such circumstances, speec...

AI Technical Summary

Benefits of technology

"The invention is a system that improves the quality of speech and noise communication signals. It does this by dividing the signal into multiple frequency bands and estimating the power of each band over time. This information is then used to generate power band signals with corresponding weighting factors. These factors are applied to the original signal to create a weighted frequency band signal that is combined to create a better quality communication signal. This process is done with a calculator and provides a more accurate and easy way to improve communication signal quality."

Problems solved by technology

Cellular telephones are operated often in the presence of high levels of environmental background noise, such as in moving vehicles.

Such high levels of noise cause significant degradation of the speech quality at the far end receiver.

Such two-state voice activity detectors do not perform robustly under adverse conditions such as in cellular telephony environments.

In the past, inaccuracies in such power measures have limited the effectiveness of known noise cancellation systems.

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